Self-calibration methodology by normalized intensity for wavelength modulation spectroscopy measurement

A methodology of self-calibration for concentration measurement based on wavelength modulation absorption spectroscopy has been developed by normalized fixed intensity. Experimental results show that the simple self-calibration method not only effectively improves the calibration accuracy, but also greatly improves stabilization and reliability as compared with the popular method called self-calibration by 1f normalized. In addition, the proposed system do not need any additional equipment when comparing with the use of traditional wavelength modulation absorption spectrometer. The standard deviation of a concentration measurement with different optical intensity aimed on the detector has been found to be below 1.0%. The dependence of the concentration assessment on the laser intensity fluctuation has also been investigated, which shows that the method of self-calibration could be applied in the field, specially where the dust is easily splattered on the windows of the detector.